Direct mail is one of the strongest channels for repeat purchases. But one question was previously hard to answer:

“How much revenue does the postcard really generate?”

Voucher codes and responder matching, meaning total conversions, provide useful signals, but they always measure only part of the truth. The alternative until now was to create a manual control group in Excel, draw clean samples and run the analysis statistically correctly. Nobody enjoys doing that.

That is exactly why we built something new.

Create a control group

With our new feature, you can define a control group very easily in every campaign. No Excel, no manual effort, no statistics stress.

How it works

  • During campaign creation, you select your segment as usual: Shopify, Klaviyo or CSV.

  • Under “Advanced settings”, you then enter how large your control group should be, for example 10%.

  • PostPal immediately shows you how many contacts that equals.

  • These contacts are automatically marked and receive their own event pushed to Klaviyo. This ensures they are treated like the mailing group in future campaigns and that the results remain meaningful.

Control group during campaign creation under segment definition

Once the mailing has arrived with your customers, you can compare the control group results on the right with the mailing group on the left on the mailing performance page.

Comparison of mailing results with the control group

In this example, the control group has a conversion rate of 4.78%, while the mailing group has 8.31%. The incremental uplift, meaning the real conversion rate, is therefore 3.53%. The campaign delivered 1,589 conversions and generated €87,753.77 in revenue.

In the next iteration, we will automatically extrapolate the control group for you and subtract it from the overall result. That way, you will immediately see the true campaign success at a glance.

With the new control group, you can now reliably track the actual impact of your print campaigns without effort. No experiment workaround, no estimate and no gut feeling.

Why use a control group at all?

If you want to learn more about the theory behind control groups and why they are the gold standard for measuring true marketing success, you can find a detailed article here on how control groups work in direct marketing.